Based on the operational experience of the experimental fast reactor BR-5, the prototype of a full-scale fast-reactor power station of 350 Mwe and 1000 Mwt is being designed. Fuel elements are stainless steel tubes filled with uranium and plutonium dioxides, ribbed for spacing, and inserted into subassemblies. The radial blanket consists of cylindrical elements filled with depleted UO{sub 2} and inserted into subassemblies. The reactor is controlled by B{sub 4}C elements. Burnup reactivity change is compensated by movable subassemblies. Reactivity changes due to heat and power rise are compensated by B{sub 4}C subassemblies. Similar B{sub 4}C subassemblies are used for reactor scram. The shieldling, fuel charge and discharge mechanism, pumps, heat exchangers, and steam generators are described, and the coolant parameters of the primary, secondary, and third loops are given. (M.J.T.)